1. Field of the Invention
The invention relates to methods and apparatus for washing, cleansing and lavage utilizing pressurized oscillating liquid jets to remove particles, liquids, gels, oils, fats and microbial organisms from objects.
2. Brief Description of Related Art
The cleansing of objects, the washing of skin and the lavage of wounds has been the object of numerous inventions in the past. The cleansing of objects, in particular as it relates to the washing of human and animal body parts and skin for the purpose of reducing pathogens that may be transmitted to other objects or parties, is of critical interest to the medical, surgical and food handling communities. The ability to remove pathogens such as, for example, both transient Escherichia coli (E. coli), Salmonella and resident Staphylococcus aureus pathogens is critical to the minimization of the transmittal of such bacteria. Transient micro-organisms are generally found on the surface of the skin and are picked up by handling of raw meats and from previously contaminated surfaces and are generally readily washed off by any number of washing techniques. The resident micro-organisms found embedded in the pores and folds of the skin and tissues generally cannot be readily removed. S. aureus is found on over 30-percent of adult humans (Miller et al. "A Field Study Evaluating the Effectiveness of Different hand Soaps and Sanitizers," Dairy, Food and Environmental Sanitation, Vol.14, No.3, March 1994). Fast food establishments are particularly prone to passing on such pathogens merely because large quantities of food are handled and served to the public and because of the lack of adequate training and education in hygiene required of food handling personnel. While incidents such as the recent E. Coli outbreak in hamburger meat are relatively rare, they are nonetheless significant due to the large percentage of deaths attributed thereto. Even more significant, albeit far less publicized, is the large number of deaths occurring from hepatitis B in Pacific rim countries due to ingestion of contaminated sushi and raw meat that have been infected by food handlers to whom personal hygiene and cleanliness is not part of social customs or mores.
The critical care of injured or wounded personnel relies to a great extent on the degree to which pathogens, and non-pathogens which can become pathogenic in the wound environment, can be eliminated from wounds prior to their being operated on, consequently minimizing the incidence of sepsis, infection, and disease. Until the 20th century the majority of war dead could be attributed to lack of sanitation and infection of, often, non-critical wounds; and, even during the Vietnam Conflict, death rates of 50 to 100 percent of the wounded were not uncommon. The tropical climate engendered significant pathogenic activity.
Conventional scrubbing of skin, for example with cloths or brushes and soaps (both ordinary and antibacterial), is only moderately effective when a short procedure, such as is normally employed by marginally dedicated people, is used. Typically, about 50 percent removal occurs (Miller et al.). Surgical scrubs, which may last as long as 5-15 minutes, depending on the diligence and experience of the personnel, may remove as much as 90-91 percent of the transient micro-organisms, but very few, if any, of the resident micro-organisms. A major problem with frequent scrubbing is the "dish-pan-hands" syndrome, redness, irritation and epidermal loss, which is associated with abrasion as well as increased sensitivity to chemicals when they are forcibly scrubbed on the skin. With present-day concerns about costs and efficiency, particularly with managed health care, time consumed in thorough hand washing becomes a major cost driver. When a 15 minute scrub is required even before a short procedure, this can limit the number of procedures that can be conducted during any given day.
It is well known in the art that pressurized liquids can be used to wash away materials and that, in combination with appropriate surfactants, detergents, soaps and anti-bacterial chemicals, the effectiveness of the removal of pathogens can be enhanced. By providing sweeping action to the pressurized jet stream, large areas can be washed and the angle at which the pressurized liquid jet impinges on a surface can be changed to provide an increased force on surface objects and particles to push them off the surface to which they adhere.
Pulsing the liquid is also taught in the art where the impulse forces of the liquid stream acting against particles helps to dislodge them. The oral irrigator is a good example of the use of a pulsating jet of water to help remove plaque from teeth. A major disadvantage of the pulsating irrigator is, however, that the high pressure axial pulses of liquid often tend to force bacteria and pathogens further under the gums, thereby actually promoting infection by introducing the bacteria directly into the blood stream.
Pulsating jets of water have also been adapted to pre-surgical cleansing of skin on the hands and forearms, and a particularly important effect is taught by Bhaskar et al. (U.S. Pat. No. 3,757,806) in their Pulsating Hydrojet Lavage Device, and by Decker et al. "A Rapid Method for the Presurgical Cleansing of Hands," Obstetrics and Gynecology, Vol. 51, No. 1, January 1978, wherein a plurality of nozzles located circumferentially and in depth in such a way as to provide coverage of a human hand and forearm, provide pulsating jets which pulse at a frequency that is in resonance with the dynamic response of the human epidermis, about 20-25 Hz, thereby causing the skin to resonantly vibrate wherein the pores, ridges and crevices of the skin alternately expand and contract in such a way as to loosen resident pathogens, such as Staphylococcus aureus, as well as embedded oils, greases, and dirt/solid particles. High pressure (50-80 psi) water jets flush the loosened matter away while depositing antibacterial chemicals as desired. Even when the device is operated at a frequency well above that of the skin resonance, 85 Hz, Bhaskar et al. show that their device provides comparable, if not better, bacteria removal in 90 seconds than a 10 minute surgical scrub. However, the same deleterious effect of embedding bacteria by the axial pulses may occur, albeit not to the same extent as in the oral irrigator.
Similar pulsating stream effectiveness is described in the lavage and debridement of wounds by Gross et al. ("The Effect of Pulsating Water Jet Lavage on Experimental Contaminated Wounds," J. Oral Surgery, Vol.29, March 1971) where a significant reduction in post-operative infections in test rats was observed.
Stouffer and Bauer (U.S. Pat. No. 3,973,558) with their swept jet oral irrigator teach that a similar resonant effect can be achieved on human gum tissue by sweeping a high pressure jet at the resonant frequency of gum tissue. Also by sweeping the jet over a substantial angle, up to about 90.degree., their device can provide for greater areal coverage thereby reducing the time required to effect cleansing. By using a fluidic oscillator they oscillate the fluid jet itself rather than the jet-issuing body thereby eliminating the need for costly and unreliable mechanically moving parts.
Despite the above teachings, currently commercially available hand washing systems, as exemplified and described in U.S. Pat. Nos. 3,699,984; 3,918,987; 4,219,367; 4,402,331; 4,817,651; 4,925,495; and 5,193,563, have not taken advantage of them. Typical of these devices is the invention of Crisp et al. Hand and Forearm Cleansing Apparatus, which shows a complex mechanical arrangement of rotating cylinders with spray nozzles therein, which only provide rotating steady jets of water to provide for good areal coverage but not in a manner as to stimulate any skin resonance effects. All of the above cited devices require electrical power, which is in itself dangerous in the wet environment, to operate a myriad of mechanically moving parts including pumps and rotating jet issuing bodies. The mechanical complexity of these systems results in a high cost which makes such systems unattractive to fast food establishments which operate on a very slim profit margin. While the cost of these systems would not be prohibitive in medical applications, the bulk, complexity, noise, and questionable reliability makes them unattractive for operating room use.
Sweeping jets without use of electricity or mechanically moving parts by using fluidic oscillation means is known in the art, the Stauffer et al. swept jet oral irrigator device, and the Bray (U.S. Pat. No. 4,463,904) windshield washer spray nozzle, being exemplary thereof. However, within the art of fluidic oscillators there are those that have different attributes and some are more suited to cleansing than others. The Stauffer et al. and Bray oscillators, while providing an oscillating jet, do so with relatively long dwell at the extremes of the jet spray so that there is little effectiveness in the middle of the fan spray. For gum massage and flushing this is not a detriment but for washing of large areas of skin this would require large, controlled, repetitive motion and reorientation of the hands and forearms to ensure proper coverage. Lack of proper repeatibility could result in less than optimal results and the requirement for appropriate training in the use of such a system would make constant supervision necessary and somewhat unreliable. Uniform spray coverage with a fluidic oscillator is taught in the art by Bauer (U.S. Pat. Nos. 4,231,519 and Re. 33,159). Indeed, Bauer teaches the art of adjusting spray angle as well as uniformity. Frequency of the oscillating jet, as well as droplet breakup characteristics, are adjusted by the overall size of the device and the supply pressure of the liquid. Making the device larger reduces frequency and the frequency increases as the square root of the supply pressure (linearly with the fluid velocity).